Stockholders' Equity - Stock Option Activity (Details) - $ / shares	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Number of Shares
Outstanding, beginning balance (in shares)	1,686,902	2,806,364	2,845,866
Granted (in shares)	92,610	409,368	299,397
Exercised (in shares)	(580,861)	(1,384,647)	(250,823)
Canceled (in shares)	(36,146)	(144,183)	(88,076)
Outstanding, ending balance (in shares)	1,162,505	1,686,902	2,806,364	2,845,866
Weighted- Average Exercise Price Per Share
Outstanding, beginning balance (in dollars per share)	$ 7.00	$ 4.75	$ 4.21
Granted (in dollars per share)	9.49	9.59	8.60
Exercised (in dollars per share)	6.15	3.25	2.96
Canceled (in dollars per share)	10.76	6.62	5.23
Outstanding, ending balance (in dollars per share)	$ 7.51	$ 7.00	$ 4.75	$ 4.21
Weighted- Average Remaining Contractual Term (in Years)
Outstanding	6 years 1 month 6 days	5 years 4 months 24 days	4 years 7 months 6 days	5 years 4 months 24 days
Vested and Expected to Vest at September 30, 2020
Outstanding (in shares)	1,162,505
Exercisable (in shares)	775,861
Outstanding, weighted average exercise price (in dollars per share)	$ 7.51
Exercisable, weighted average exercise price (in dollars per share)	$ 6.54
Outstanding, weighted average remaining contractual term (in years)	6 years 1 month 6 days
Exercisable, weighted average remaining contractual term (in years)	5 years